﻿using System;
using System.Collections.Generic;
using System.DrawingCore;
using System.DrawingCore.Imaging;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;

namespace System {
    /// <summary>
    /// 验证码
    /// </summary>
    public class VerifyCode {
        public byte[] GetVerifyCode(out string chkCode) {
            int codeW = 80;
            int codeH = 30;
            int fontSize = 16;
            chkCode = string.Empty;
            //颜色列表，用于验证码、噪线、噪点 
            Color[] color = { Color.Black,Color.Red,Color.Blue,Color.Green,Color.Orange,Color.Brown,Color.Brown,Color.DarkBlue };
            //字体列表，用于验证码 
            string[] font = { "Times New Roman" };
            //验证码的字符集，去掉了一些容易混淆的字符 
            char[] character = { '1','2','3','4','5','6','7','8','9','a','b','d','e','f','h','k','m','n','r','x','y','A','B','C','D','E','F','G','H','J','K','L','M','N','P','R','S','T','W','X','Y' };
            Random rnd = new Random();
            //生成验证码字符串 
            for(int i = 0;i < 4;i++) {
                chkCode += character[rnd.Next(character.Length)];
            }
            //写入 SetItem、验证码加密
            ConfigurationHelper.SetValue("agile_session_verifycode",chkCode.ToLower());
            //创建画布
            Bitmap bmp = new Bitmap(codeW,codeH);
            Graphics g = Graphics.FromImage(bmp);
            g.Clear(Color.White);
            //画噪线 
            for(int i = 0;i < 1;i++) {
                int x1 = rnd.Next(codeW);
                int y1 = rnd.Next(codeH);
                int x2 = rnd.Next(codeW);
                int y2 = rnd.Next(codeH);
                Color clr = color[rnd.Next(color.Length)];
                g.DrawLine(new Pen(clr),x1,y1,x2,y2);
            }
            //画验证码字符串 
            for(int i = 0;i < chkCode.Length;i++) {
                string fnt = font[rnd.Next(font.Length)];
                Font ft = new Font(fnt,fontSize);
                Color clr = color[rnd.Next(color.Length)];
                g.DrawString(chkCode[i].ToString(),ft,new SolidBrush(clr),(float)i * 18,(float)0);
            }
            //将验证码图片写入内存流，并将其以 "image/Png" 格式输出 
            MemoryStream ms = new MemoryStream();
            try {
                bmp.Save(ms,ImageFormat.Png);
                return ms.ToArray();
            } catch(Exception) {
                return null;
            } finally {
                g.Dispose();
                bmp.Dispose();
            }
        }
        public bool IsVerifyCode(string verifycode) {
            string item = ConfigurationHelper.GetValue<string>("agile_session_verifycode");
            if(string.IsNullOrWhiteSpace(verifycode) || string.IsNullOrWhiteSpace(item) || verifycode.ToLower() != item) {
                return false;
            }
            return true;
        }
    }
}
